Hitachi, Ltd.

Hitachi Const. Machinery Co.

Toshimi Sasaki

Toshiyuki Kajiwara

Tomoaki Kimura

Keiichi Kuniya

Mitsuo Nihei

Masahisa Sobue

Kimihiko Akahori

Sensuke Okada

Masahisa Inagaki

Takao Funamoto

Akihiko Yamamoto

Keiichi Koike

Yoshiro Ibaraki

Satoshi Kokura

Takashi Haramaki

Kousei Nagayama

Keiji Taguchi

Takeshi Hachisu

Nobuyoshi Hidao

Tetsuo Matsumoto

Ryutaro Jimbou

A roller for rolling mill comprising an entirely non-metallic sintered body composed principally of at least one material selected from silicon carbide, silicon nitride, sialon, alumina and zirconia and having a relative density which is at least 96% of the theoretical density, the roller having an initial crown in the range of -300 .mu.m to +300 .mu.m, is provided. This roller for rolling mill has a high hardness and high wear resistance and can be used as a work roll.

Rollers for rolling mills

A roller for rolling mill comprising an entirely non-metallic sintered body composed principally of at least one material selected from silicon carbide, silicon nitride, sialon, alumina and zirconia and having a relative density which is at least 96% of the theoretical density of the sintered body, the roller having an initial crown in the range of -300 .mu.m to +300 .mu.m, is provided. This roller for rolling mill has a high hardness and high wear resistance and can be used as a work roll.

Disclosed is a diffusion bonding method which can be applied to superalloys and comprises forming in advance an alloy layer containing an additional element or elements having a higher diffusion speed than that of the principal constituent element of a base metal and a lower melting point than that of the base metal on the joint surface of the base metal consisting of a heat-resistant superalloy based on Co, Ni, Fe, Ti or the like, and bringing the joint surfaces into contact so as to diffuse B.

Diffusion bonding method using a high energy beam

A quenching method wherein an object to be quenched is sprayed with a mixed spray jet of a liquid and a gas. The diameter of droplets in the mixed spray jet is from 50 to 200 .mu.m, and the mixing ratio between the liquid and the gas is varied during the period from the start to the end of cooling. Also disclosed is a quenching apparatus having nozzles for spraying an object to be quenched with a mixed spray jet of a liquid and a gas, a liquid supply source for supplying a pressurized liquid, and a gas supply source for supplying a pressurized gas. Each of the nozzles has a liquid-jetting port formed in the surface opened to the atmosphere and a gas-jetting port annularly formed around the liquid-jetting port on the same plane. The liquid-jetting port is communicated with the liquid supply source, while the gas-jetting port is communicated with the gas supply source. A flow rate regulating valve for regulating the flow rate of the pressurized liquid is disposed between the liquid-jetting port and the liquid supply source, while a flow rate regulating valve for regulating the flow rate of the pressurized gas is disposed between the gas-jetting port and the gas supply source.

Method and apparatus for quenching

Titanium alloy or cast titanium alloy is heat-treated in vacuum or a neutral atmosphere to convert the abnormal structure of the alloy to normal .alpha. or .alpha. + .beta. structure. The titanium alloy or cast titanium alloy thus heat-treated can have sufficiently good material characteristics by the ordinary successive heat treatments.

Method for heat treatment of titanium alloy

A heat insulating coating material is provided by admixing an alkali metal silicate binder and water with aggregates comprising silica-containing inorganic refractory fibers, silica-containing porous refractory materials and silica-containing powdery refractory materials. The alkali metal silicate binder can be replaced by a phosphate binder, depending upon the nature of an atmosphere, and finely divided metals can be incorporated into the aggregates.

Heat insulating coating material

Growing community of inventors

Mito, Japan

Toshimi Sasaki